It is generally known that, in multilayer color photographic materials having blue-sensitive, green-sensitive and red-sensitive silver halide emulsion layers, scattering of light by silver halide grains tends to reduce the sharpness of the lower emulsion layers.
Color photographic photosensitive materials in which sharpness, sensitivity and graininess are improved by use of a tabular silver halide emulsion are disclosed in U.S. Pat. Nos. 4,439,520 and 4,433,048. Sharpness is normally expressed as an MTF value, and the details thereof are described in James, Theory of the Photographic Process, 4th Edition, p. 596 and p. 104, Macmillan Publishing Co., Ltd. (1977). It is well known that, using the MTF representation, the sharpness of the photosensitive material displays a frequency dependency having a pattern such as that of curve (a) of the Figure, for example, and that the pattern is the result of optical scattering in the emulsion layers of the photosensitive material and of effects caused by development.
The improvement in sharpness using tabular grain emulsions does not always result in a significant improvement over the entirety of the MTF frequencies. However, what is frequently observed is that use of such emulsions results in an improvement which, in contrast to the pattern of curve (a) in the Figure, is restricted mainly to the high frequency region as illustrated by curve (b) in the Figure or in an improvement in the high frequency region together with a deterioration in the low frequency region as illustrated by curve (c) in the Figure.
In general, low-frequency MTF values of 20 lines/mm or less affect visually perceived sharpness more than high frequency MTF values and there is a particular demand for an improvement in this respect.